1. Field of the Invention
This invention relates to a fuel feeding pipe formed by connecting together a first feed oil pipe which is a conduit extending from an oil filler port of an automobile and a second feed oil pipe which is a conduit projecting from a fuel tank.
2. Prior Art
General fuel feeding pipes for an automobile have been formed by manufacturing separately a conduit (hereinafter defined as a first feed oil pipe) extending from an oil filler port and a conduit (hereinafter defined as a second feed oil pipe) projecting from a fuel tank, and then connecting the resultant two feed oil pipes together during an installation process of the feed oil pipes to a vehicle body. In this fuel feeding pipe, the first and second oil pipes are connected together via a rubber or a resin pipe for the purpose of setting free the arrangement relation between the two feed oil pipes and of preventing the influence of vibrations of the fuel tank from being exerted on the first feed oil pipe. However, this rubber or resin pipe has the property of permeating fuel vapor through a wall thereof, and causes atmospheric pollution to occur. Therefore, in recent years, a fuel feeding pipe formed by directly connecting first and second feed oil pipes together without using a rubber or resin pipe has been proposed. For example, in the inventions disclosed in JP-A-2001-191802, JP-A-11-048801 and Japanese Patent No. 2566279, a second feed oil pipe is not provided, and a flange provided on an end portion of a first feed oil pipe is connected in a surface contacting state to a fuel tank. On the other hand, in the inventions disclosed in JP-A-2001-097054, JP-B-05-042893, JP-A-07-127783 and U.S. Pat. No. 6,305,408, first and second feed oil pipes are connected together by a metal joint.
However, the fuel feeding pipes described above have the following problems.
First, the case of the fuel feeding pipe formed by connecting the flange provided on an end portion of the first feed oil pipe to the fuel tank in a surface contacting state will be described. Since it becomes necessary that a packing is provided between the flange and fuel tank so as to secure hermeticity thereof, the durability of the packing becomes a problem. In addition, a whirl-stop member, such as a spring washer for preventing the loosening of the packing also becomes necessary, and this causes an increase in the number of parts and the number of assembling processes. Moreover, due to the structure for fixing the first feed oil pipe to the fuel tank, the transferring of the first feed oil pipe to an assembly line when a specially long first feed oil pipe is used is rendered difficult, and the replacement of parts of the first feed oil pipe also becomes difficult.
Next, the case where the first and second feed oil pipes are connected together by a metal joint will now be described. In this case, it is necessary to use a joint neither loosened nor coming off even when the vibrations of an automobile occur. The loosening and separation of the joint causes the leakage of a fuel and in its turn the ignition of the fuel. However, the use of a solid joint in which neither the loosening nor the separation thereof occurs causes an increase in the number of parts and the number of assembling processes, and, moreover, renders the replacement of parts difficult.
In view of the above, therefore, the inventors of the invention have investigated to develop a fuel feeding pipe connected to a fuel tank of an automobile, which attains (1) the satisfaction of a basic demand for the minimization of the permeation of a fuel through the wall of the pipe, (2) the convenient replacement of parts based on the easily removable pipe, (3) the securing of the necessary and sufficient hermeticity of the pipe in various kinds of environments, and (4) the prevention of the loosening and separation, which are ascribed to the vibrations and collision of an automobile, of a connecting portion of the pipe.